The present invention pertains to blades for rotary lawnmowers and, more particularly, to a tool useful in attaching a cutting blade insert to a mower blade and for removing the insert after it has worn or become damaged.
Rotary lawnmower blades in which the blade cutting edge is made as a separate insert are well known in the art. Such a cutting edge insert is shown, for example, in U.S. Pat. No. 6,182,430. The mower blade itself may be of a conventional construction, being long and narrow and relatively thin with a cutting edge insert attached to the blade body at opposite ends and with oppositely oriented cutting edges. The blade edge insert is typically received in a shallow recess on the underside of the mower blade body and is secured in the recess with a sliding and wedging press fit connection where the insert is held against the undersides of headed connectors, such as rivets, that extend perpendicular from the flat face of the recess. The blade edge insert is provided with a number of linearly aligned key hole slots that receive the headed connectors after which the insert is tapped or pushed to force the insert into wedging engagement with the undersides of the connector heads. This establishes the fully attached position of the insert.
When the blade edge insert becomes dull or damaged, it can be easily replaced, instead of having to replace the entire blade body. The blade edge insert is removed by moving it in the opposite linear direction in the shallow recess by tapping the insert and causing it to slide from under the connector heads and release the wedging press fit engagement by which the insert is held. Tools are required both to attach the insert and to remove it, one typical method being to tap or drive the insert in the desired direction with a screw driver or chisel and a hammer. This is oftentimes a difficult and potentially dangerous task because the mower blade and cutting edge are not always readily accessible and the cutting insert itself may not have a removal and attachment contact surface easily reached by the tip of a screw driver or chisel.
In addition, the blade cutting edge insert often gets jammed more tightly in its attached position due to grass, dirt and other debris being jammed into crevices or openings between the blade body and the insert. Also, inadvertent contact by the blade edge with obstacles on the ground may cause additional jamming or distortion of the insert, making it very difficult to remove.
Although a number of tools have been proposed for the removal and attachment of a blade cutting edge insert, none has proved to be particularly useful. One of the problems with using a screw driver or chisel and hammer is that inadvertent slipping of the tools may bring the user into contact with the sharp cutting edge of the insert.